CCS/PGA900: HOW to understand PGA900 PGAIN

chennangan

Intellectual 750 points

Part Number: PGA900

Tool/software: Code Composer Studio

How to understand PGain In PGA900.

As TGain , when input of TGain is 0.1mv

,I can read 0.2mv on the register of TADC_DATA1-3 as t select T_GAIN_2_V_V

And I can read 0.5mv on the register of TADC_DATA1-3 as t select T_GAIN_5_V_V.

It looks like a multiple on the register of TADC_DATA1-3.

But It doesn't look like a multiple on the register of PADC_DATA1-3.

So how to define PGain.

over 6 years ago

0 Scott Cummins over 6 years ago

TI__Mastermind 31655 points

Hello,

The PGAIN is defined using the table below:

What are you reading versus what you expected?

Regards,

0 chennangan over 6 years ago in reply to Scott Cummins

Intellectual 750 points

When the voltage measured on VINPP and VINPN pins is 0.00333v, the value of PDATA register is 0X37000,

and the voltage becomes 0.00800V, the value of the PDATA register is 0x27000,

It seems to be out of direct proportion.

My configuration as following:

ADC_Config(ADC_CFG_1_ADC_ENABLE); /* ADC is enabled */

ADC_Pchannel_Config(ADC_ENABLE | ADC_DECI_RATE_128US |ADC_ENABLE_24BIT|
ADC_INT_RATE_EVERY_SAMPLE, 0X07);

BRDG_CTRL_CONFIG(VBRDG_CTRL_2_5V|BRDG_EN);//output VBRG

0 Scott Cummins over 6 years ago in reply to chennangan

TI__Mastermind 31655 points

Is the ADC code always decreasing for an increasing differential voltage? Can you share your schematic? Are you certain that the voltages on the input pins are not swapped?

Regards,

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CCS/PGA900: HOW to understand PGA900 PGAIN